RD=R does not suppress checkpoint restarts:

• If the processing program executed in a job step does not include a CHKPT macro instruction, RD=R allows the system to restart execution at the beginning of the abnormally terminated step.
• If the program includes a CHKPT macro instruction, RD=R allows the system to restart execution at the beginning of the step, if the step abnormally terminates before the CHKPT macro instruction is executed.
• If the step abnormally terminates after the CHKPT macro instruction is executed, only checkpoint restart can occur. If you cancel the affects of the CHKPT macro instruction before the system performs a checkpoint restart, the request for automatic step restart is again in effect.

RD=RNC suppresses automatic and deferred checkpoint restarts. It suppresses:

• Any CHKPT macro instruction in the processing program: That is, the operator cannot perform an automatic checkpoint restart, and the system is not to perform a deferred checkpoint restart if the job is resubmitted.
• The DD statement CHKPT parameter.
• The checkpoint at end-of-volume (EOV) facility.

RD=NR suppresses automatic checkpoint restart but permits deferred checkpoint restarts. It permits:

• A CHKPT macro instruction to establish a checkpoint.
• The job to be resubmitted for restart at the checkpoint. On the JOB statement when resubmitting the job, specify the checkpoint in the RESTART parameter.

RD=NC suppresses automatic and deferred checkpoint restarts. It suppresses:

• Any CHKPT macro instruction in the processing program.
• The DD statement CHKPT parameter.
• The checkpoint at EOV facility.